safety and immunogenicity of tdap vaccine compared to dtap vaccine in children 4 to 6 years of age

Conditions: Tetanus; Diphtheria; Pertussis

Summary: currently, there is no 5-component acellular pertussis vaccine licensed for the 5th dose in us children aged 4 to 6 years.this study is aimed at providing evidence of sero-protection, booster response and safety of this formulation as a 5th dose. primary objective: - to compare the immune responses of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (tdap) vaccine to diphtheria, tetanus and acellular pertussis (dtap) vaccine (all antigens) when each is administered as a 5th dose and given concurrently, to children aged 4 to 6 years. secondary/observational objectives: * to compare the immune responses for pertussis antigens of tdap vaccine to dtap vaccine (for pertussis antigens) when each is administered as a 5th dose and given concurrently, to children aged 4 to 6 years. * to present the long-term immunogenicity at 1-, 3-, and 5-years post-vaccination after each long-term follow-up. * to describe the safety profile following vaccine administration.


Eligibility criteria:
inclusion criteria : * healthy, as determined by medical history and physical examination. * aged 4 to 6 (\< 7) years at the time of study vaccination on day 0. * signed and dated informed consent form that has been approved by the institutional review board (irb) by the parent or legally authorized representative. * signed and dated informed assent form from the subject if required by the irb. * able to attend scheduled visits at visit 1 and visit 2 and able to comply with all trial procedures. subjects will be invited to participate in the long-term immunogenicity follow-up study but a commitment to participate in the long-term is not required as an inclusion criterion. * documented vaccination history of 4 previous doses of daptacel according to the recommended national immunization schedule for diphtheria, tetanus and acellular pertussis (dtap). exclusion criteria : * participation in another clinical trial in the 4 weeks preceding the trial vaccination. * planned participation in another clinical trial during the original trial period. * congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroids therapy. * systemic hypersensitivity to any of the vaccine components or history of life-threatening reaction to the trial vaccine or a vaccine containing the same substances. * chronic illness at a stage that could interfere with trial conduct or completion. * blood or blood-derived products received in the past 3 months. * receipt of any other vaccine within 30 days prior to study vaccination, or planning to receive another vaccine within 30 days before the visit 2 blood draw (with the exception of the annual influenza vaccine). * history of diphtheria, tetanus or pertussis infection (confirmed either serologically or microbiologically). * thrombocytopenia or bleeding disorder contraindicating intra muscular vaccination.

Keywords: tetanus; diphtheria; pertussis; adacel; daptacel